Intel Pentium 4 Processor In the 423-pin Package Thermal Design Guidelines

Pentium® 4 processor in the 423-pin package Thermal Design Guidelines
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functioning or allow a graceful system shutdown. If no thermal management action is taken, the silicon temperature
may exceed ~135°C causing THERMTRIP# to go active and shut down the processor. Regardless of the system
design requirements or cooling solution ability, the Thermal Monitor feature must still be enabled to guarantee
proper processor operation.
9 CONCLUSION
As the complexity of today's microprocessors continues to increase, so do the power dissipation requirements. Care
must be taken to ensure that the additional power is properly dissipated. Heat can be dissipated using passive heat
sinks, fans and/or active cooling devices. Incorporating ducted airflow solutions into the system thermal design can
yield additional margin.
The size and type of the heat sink, as well as the output of the fan can be varied to balance size, cost, and space
constraints with acoustic noise. This document has presented the conditions and requirements for designing a heat
sink solution for a Pentium® 4 processor-based system. Properly designed solutions provide adequate cooling to
maintain the Pentium 4 processor within its thermal specification. This is accomplished by providing a low local
ambient temperature and creating a minimal thermal resistance to that local ambient temperature. Fan heat sinks or
ducting can be used to cool the processor if proper package temperatures cannot be maintained otherwise. By
maintaining the processor's case temperature at the values specified in the processor Datasheet, a system designer
can be confident of proper functionality and reliability of these processors.
The Pentium 4 processor has thermal management logic integrated into the processor silicon. This circuit must be
configured to automatically control the processor temperature through the use of the Thermal Monitor feature. At a
factory-calibrated temperature, the processor will periodically stop the internal clocks in order to reduce power
consumption and cool down the processor. Various registers and bus signals are available to monitor and control the
processor thermal status.
A chassis cooling solution designed to the TDP as specified in the Datasheet will adequately cool the processor to a
level where activation of the Thermal Monitor feature is either very rare or non-existent. Various levels of
performance versus cooling capacity are available and must be understood before designing a chassis. Automatic
thermal management must be used as part of the total system thermal solution.